The present invention relates to portable navigation systems. More specifically, embodiments of the present invention relate to low-cost inertial dead-reckoning navigation systems and methods.
Many current outdoor portable navigation systems rely upon signals such as GPS signals, RF (e.g. cell-tower) signals, and the like, to determine the user's location and heading. The inventor believes that such solutions, are often not applicable or useful for indoor navigation. One drawback is that GPS signals and RF signals often do not penetrate deeply into buildings, accordingly such a navigation system may be unreliable. Another drawback is that such signals are often low resolution and are not accurate enough to help a user navigate within an indoor environment where accuracy within feet is often required. Yet another drawback is that such signals typically require power-intensive receivers/processors to provide positional data. Such power-hungry processing would also reduce how long the user could use such a navigation system.
Some current approaches to indoor navigation systems assumes that a user will rely upon a magnetic heading of the device to determine the user heading. It also assumes that the user will keep a device aligned in a specific orientation. By requiring the specific orientation, the magnetic heading of the device will always have a constant relationship to user direction of travel.
While such assumptions may be reasonable to navigation systems affixed to a vehicle, e.g. a shopping cart, a car, the inventor believes these assumptions are unreasonable in the context of hand-held portable navigation systems. More specifically, the inventor believes that for practical indoor navigation applications, it is unrealistic to tell a user to hold the device in a fixed and rigid orientation throughout a store.
Instead, the inventor believes solutions need to be developed that take into account that mobile devices are often held in the pocket, hand, purse, etc., and the location relative to the user can be changed during use depending on how the device is currently being used (phone, music player, video display, game, etc.).
In light of the above, it is desired to have portable navigation systems with reduced power consumption without the drawbacks described above.